Scientists have found that Covaxin, which is an inactivated whole-virion vaccine, induces robust immune memory to SARS-CoV-2 and variants of concern that stay for at least six months after vaccination and induces memory T cells that can respond robustly against the variants. This may help in controlling the virus load and thus, reduce the disease severity.
BBV152/Covaxin is based on an Asp614Gly variant and formulated with a toll-like receptor (TLR) 7/8 agonist molecule (imidazoquinolin) adsorbed to alum. It was the first alum-imidazoquinolin adjuvanted vaccine produced in India and received emergency use authorisation from WHO for use in a large population.
Although the clinical trial data was available for vaccine efficacy, important questions remained unanswered for evidence-based policy making particularly. These included whether the vaccine induces immune memory, how long the vaccine-induced memory persists, and whether these memory responses are able to sustain against the SARS-CoV-2 variants.
